[syslinux] pxelinux never OACKs tftp server response

H. Peter Anvin hpa at zytor.com
Wed Mar 7 22:45:55 PST 2007


Eric Irrgang wrote:
> After the PXE PROM code downloads and runs the pxelinux.0 image and it 
> tries to download config information the client stops acknowledging the 
> server OACK packets from the server.
> 
> pxelinux from syslinux 3.11 from Fedora RPM, accessing Solaris 10 in.tftpd
> 
> The tftp client in pxelinux.0 sends a tftp file read request with extended 
> options tsize \00 0 \00 blksize \00 1440 \00 and then the server responds 
> with opcode 6 (as per RFC 2347) and tsize \00 79 \00 blksize \00 1440 \00 
> and then the client just retries a few times and tries the next config 
> file.
> 
> The PXE card is using the blksize extended option with 1456 bytes and it 
> is working fine.
> 
> Something I notice is that the servers response never comes from port 69 
> but from an arbitrary higher-numbered port.  The PXE PROM just ACKs 
> (opcode 4) back to the port from which it received the OACK and the 
> conversation continues, but I wonder if the tftp client code in pxelinux 
> doesn't go for that.

No, that's all consistent with the spec.  Could you send me (off list) a 
wireshark (ethereal) trace file, or if that's not practical, the output 
of "tcpdump -e -s 2000 -XX -vv" with the appropriate filter options?

	-hpa




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